From 3GPP Release 7 and later, the PCC (Policy and Charging Control) interface which is the interface between the PCEF (Policy and Charging Enforcement Function) and the Policy and Charging Rules Function (PCRF) is used to control the quality of service in a cellular system or network, the control being carried out from the PCRF, with the quality of service being defined by the parameters QCI (QoS Class Index, QoS=Quality of Service) and ARP (Allocation and Retention Priority).